Base stations may employ multiple-input multiple-output (MIMO) antenna arrays in order to improve reception performance when communicating with mobile devices. A MIMO antenna array may include a large number of antenna elements in some cases, which may be beneficial in terms of diversity gain or the ability to receive signals from multiple mobile devices in common time and frequency resources. However, resource collisions are more likely as greater numbers of antennas are used. Accordingly, there is a general need to alleviate collision issues in MIMO systems.